There has been used a water pressure transfer method in order to decorate a surface of an article having a complicated three-dimensional surface in which a water pressure transfer film having a print pattern of non-water solubility on a water-soluble film is floated on a water surface in a transfer tub, after this water-soluble film of the water pressure transfer film is made wet with water, an article (an object to be pattern-transferred) is forced underwater while contacting the print pattern of the water pressure transfer film and the print pattern of the water pressure transfer film is transferred to the surface of the article using water pressure generated relative to the surface of the article when the article is forced underwater to form a decorative layer is formed on the surface of the article.
In general, since the water pressure transfer film has the print pattern printed and dried on the water-soluble film and is stored while it is wound in the form of roll, the ink of the print pattern is in the dry state where the ink loses its adhesion. Thus, it is required to apply an activating agent or solvents such as thinner to make it the wet state (recover the state of having an adhesion), which is like the state immediately after the print pattern is printed. This treatment normally called an activation process.
The decorative layer thus formed on the surface of the article by the water pressure transfer is required to have the physical and chemical surface protection function such as abrasion resistance, solvent resistance, chemical resistance and weather resistance and also to be adhered onto the surface of the article with high strength so as not to be removed therefrom.
The applicant has already proposed the invention for transferring the decoration layer under water pressure while imparting abrasion resistance, solvent resistance, etc. to the decoration layer itself, without having a topcoat layer on the decoration layer (refer to Patent Documents 1 through 3). According to the methods of these inventions, an ultraviolet ray hardening resin composite including a non-solvent type activation ingredient such as photo-polymerization monomer for reproducing the adhesion of the dried print pattern of the water pressure transfer film is applied on the print pattern whereby the adhesion of the print pattern is reproduced by the activation ingredient of the ultraviolet ray hardening resin composite and the print pattern is transferred onto the film-transferred object under water pressure in the state where the ultraviolet ray hardening resin composite is permeated into the whole print pattern. Therefore, when the ultraviolet ray hardening resin composite within the print pattern is hardened by irradiation of ultraviolet ray, the decoration layer has the state as if the ultraviolet ray hardening characteristic is just imparted to the decoration layer itself. Thus, the decoration layer has chemical and mechanical surface protection functions such as solvent resistance and abrasion resistance imparted to the decoration layer itself.
In order to apply the ultraviolet ray hardening resin composite onto the water pressure transfer film to thereby reproduce the adhesion of the dried print patter and permeate the ultraviolet ray hardening resin composite into the print pattern whereby the print pattern and the ultraviolet ray hardening resin composite are integrally intermingled with each other so as to be fully united with each other for imparting the ultraviolet ray hardening characteristic to the print pattern, the ultraviolet ray hardening resin composite is ideally required to have a comparatively low viscosity allowing the ultraviolet ray hardening resin composite to be permeated into the whole print pattern once dried and hardened in a uniform manner and an ink solubility allowing the ink to be dissolved to recover the adhesion of the ink and the ultraviolet ray hardening resin composite is required to be applied to the print pattern in the required amount of application on the water pressure transfer.
If the ultraviolet ray hardening resin composite has too high viscosity, then it will fail to permeate the whole print pattern in an adequate amount and if the ink solubility of the ultraviolet ray hardening resin composite is too low, then the adhesion of the print pattern in the state of dryness and solidification will be never reproduced. If the amount of application of the ultraviolet ray hardening resin composite is too low, then the ultraviolet ray hardening resin composite will never reach the surface of the print pattern (the outer surface of the print pattern after it is transferred).
If the viscosity of the ultraviolet ray hardening resin composite is too low or if there are too much amount of application thereof, the print pattern will be broken down and there will be generated a phenomenon where the pattern fades.
Thus, in order that the adhesion of the dry print pattern is reproduced or the ultraviolet ray hardening resin composite is permeated into and fully united with the print pattern, the ultraviolet ray hardening resin composite is required to have the predetermined degree of the viscosity, the ink solubility and the amount of applications. What is meant by the state where the ultraviolet ray hardening resin is integrally united with the print pattern is not the state where it is partially mixed with the print pattern, but the state where it is wholly and preferably just uniformly with the print pattern. If the ultraviolet ray hardening resin composite might be combined with the print pattern just only on the resin composite application side thereof, but never reach the outer surface of the print pattern after it is transferred, then the surface of the decoration layer, which is the outermost surface of the decoration layer has no surface protection function such as solvent resistance and so on imparted thereto.
The commercially available conventional ultraviolet ray hardening resin composites include at least a photo-polymerization pre-polymer, a photo-polymerization monomer and a photo-polymerization initiator, but these commercially available ultraviolet ray hardening resin composites were not such products as were manufactured for intentional use in which the resin composites permeate the whole ink once dried and hardened so as to be integrally combined with the print pattern and is hardened together with the ink after the ultraviolet ray is radiated as if the ultraviolet ray hardenability is imparted to the ink. Thus, these resin composites can be applied for water pressure transfer of low or middle level where the products have the pattern looking like wooden grain, but never fully meet the water pressure transfer of high or ultrahigh level requiring precise design such as true tree feeling in the decoration of interior parts of cars. These ultraviolet ray hardening resin composites for wide use cannot be satisfactorily applied to a water pressure transfer of high or super-high grade in which a minute design quality such as true tree feeling required for decoration in a car interior article. In addition thereto, these ultraviolet ray hardening resin composites cannot be satisfactorily applied to various transfer films having huge accumulation of the past with respect to the elements of the ink such as the kind of ink or the shade to be used for the print pattern and there remain the problems in compatibility and conformity with various equipment used in the conventional water pressure transfer processing lines.
The applicant have proposed the activating agent for the water pressure transfer film applicable also to the water pressure transfer of high grade or super high grade which cannot be accomplished by the conventional general-purpose ultraviolet ray hardening resin composite (see Patent Document 4).
The activating agent according to Patent Document 4 includes a photo-polymerization pre-polymer, a photo-polymerization monomer and a photo-polymerization initiator without any inclusion of an organic solvent, the photo-polymerization pre-polymer being of 9 to 40 mass %, bi-functional photo-polymerization monomer being of 50 to 90 mass %, a photo-polymerization initiator being of 0.5 to 5 mass % and the remainder being of 0.5 to 5 mass % and has a viscosity of 10-100 CPS (25° C.) or (25 degree Celsius) and an ink solubility of 10 or more at SP value.
According to the activating agent by Patent Documents 4 proposed by the applicant, the photo-polymerization monomer of the ultraviolet ray hardening resin composite has solvent power to the ink of the print pattern as well as solvent power to the photo-polymerization pre-polymer and as a result, the activating agent has the good hardenability, the good adhesion to ABS resin, PC material, etc., a substrate on which the pattern is transferred by the water pressure transfer, the smoothness because of little contractility when it is hardened and the transparency maintained. Thus, the adhesion to the dried and solidified print pattern of the water pressure transfer film can be positively reproduced by the proper viscosity and ink solubility of the ultraviolet ray hardening resin composite and in addition thereto, since the ultraviolet ray hardening resin composite can permeate and enter into the total thickness of the print pattern from the surface of the print pattern on the side of the application thereof to the surface thereof on the opposite side so that the resin composite and the print pattern are positively and harmoniously integrated with each other through the whole of the print pattern (the whole area and thickness thereof) after the ultraviolet ray hardening, the decoration layer obtained by transferring the print pattern is hardened by ultraviolet ray over the whole decoration layer including the outside surface thereof and therefore the surface protection function by ultraviolet ray hardening is positively imparted to the decoration layer itself. Thus, the activating agent can be satisfactorily applied to the water pressure transfer of high grade and super-high grade in which a minute design quality such as true tree feeling is required and also to the abundance of kind of the print pattern of the transfer film having huge accumulation of the past and there are compatibility and conformity with the equipment used in the conventional water pressure transfer processing lines.
Since the activating agent contains the ultraviolet ray hardening resin composite having the specific viscosity of 10-100 CPS (25° C.) and the specific ink solubility of 10 or more at SP value, the solubility of the ultraviolet ray hardening resin composite can be closer to the solubility of the ink ingredient of the print pattern. Smooth coating of the activating agent to the ink ingredient of the print pattern and the permeation of the ultraviolet ray hardening resin composite into the ink ingredient can be secured by specifying the viscosity of the ultraviolet ray hardening resin composite as aforementioned.
Furthermore, the activating agent can reduce the viscosity of the photo-polymerization pre-polymer having a tendency of high viscosity and also makes the solubility of the ultraviolet ray hardening resin composite closer to the solubility of the ink ingredient of the print pattern by using the photo-polymerization monomer having the specific viscosity of 3 to 30 CPS (25° C.) and the specific ink solubility of 9 or more at SP value and therefore the property (smooth applicability) for being able to smoothly applying the activating agent onto the ink ingredient of the print pattern and the property (permeability) for permeating the ultraviolet ray hardening resin into the ink ingredient well can be secured. The ultraviolet ray hardening resin composite have the good adhesion thereof to the substrate of ABS resin, PC material, etc. the smooth applicability and the transparency fully secured when it is hardened, which can obtain the activating agent for the water pressure transfer film having all of those properties provided.
However, in general the physical strength and the membranous adhesion (including the temporal adhesion (light resistance adhesion) under ultraviolet ray exposure environment) of the membrane adhered to an article are inconsistent with each other and therefore, if one of them tries to be improved, the other will be deteriorated whereby both of them cannot be satisfactorily accomplished.
The activating agent according to Patent Documents 4 can improve the physical properties such as the strength and the chemical resistance of the decoration layer formed on the surface of the article by the water pressure transfer, can improve the original adhesion on the surface of the article to obtain the good decoration layer and can improve the light resistance to some extent to maintain the adhesion property, but as already stated, if the adhesion property including light resistance adhesion property tries to be further improved, a tendency for the strength and the chemical resistance of the decoration layer will be lowered and therefore it is difficult to satisfy both of the physical properties of the decoration layer and the adhesion property thereof.
In order to improve the characteristic of the ultraviolet ray hardening resin composite, there have been added a non-reactive resin such as acrylics polymer to the ultraviolet ray hardening resin composite (Patent Document 5 and 6).
The technique disclosed in Patent Document 5 is the one in which the non-reactive ingredient such as poly-methacrylate is added to the active energy line hardening resin composite which is the transfer layer of the transfer film to control the fluidity of the transfer layer and the technique disclosed in Patent Document 6 is the one in which the non-reactive ingredient such as acrylics polymer is added to the active energy line hardening resin composite which is the main ingredient of the coating composite for metal to reduce the volume contraction rate of the composite when it is hardened. However, in these techniques, the non-reactive ingredient only improves the fluidity and the volume contraction rate of the active energy line hardening resin composite and the two characteristics of membrane physical properties and the adhesion of the membrane, which are inconsistent with each other cannot be simultaneously satisfied.